Chief Investigators

The Study

Transcranial magnetic stimulation (TMS) is a non-invasive means of stimulating nerve cells in distinct regions of the cortex via the administration of a brief magnetic pulse to the scalp. TMS can be used to investigate aspects of brain function, including cortical excitability and cortical inhibition. When applied repeatedly, TMS can also be used to modulate cortical excitability, with subsequent therapeutic applications. We are conducting a number of TMS-based studies of autism and Asperger's disorder, and combining TMS with EEG to examine effects on brain function.

Cortical inhibition in autism and Asperger's disorder. Using various TMS motor cortical paradigms (including the response to paired pulses), we are investigating whether adolescents and young adults with autism or Asperger's disorder display evidence of impaired motor cortical inhibition. Deficient cortical inhibition could contribute to motor abnormalities in these groups, or even underlie the core symptom of repetitive and stereotyped behaviours.

Can repetitive transcranial magnetic stimulation alter motor function in autism and Asperger's disorder?This study examines whether repetitive transcranial magnetic stimulation (rTMS) can alter motor functioning in children with autism and Asperger's disorder, and thus justify the use of rTMS in a subsequent clinical trial. Motor-related EEG activity (movement-related potentials) is assessed before and after low-frequency rTMS to various motor/prefrontal regions. rTMS trains have lasting effects on cortical activity that appear to have therapeutic benefits in a number of neuropsychiatric disorders, including depression and schizophrenia.

Mirror neuron activation in autism and Asperger's disorder.Mirror neurons are cortical brain cells that fire during the performance and observation of behaviour. They have been linked to social cognition via an "embodied simulation" of other's behaviour, and are thought to facilitate an understanding of other's actions, thoughts, feelings, and intentions. Given social impairments in autism, it has been suggested that autism may involve dysfunction of the mirror neuron system, and initial evidence supports this hypothesis. We are using TMS and EEG to examine mirror neuron activation in autism and Asperger's disorder, including the mirror neuron response to observations of socially-relevant movement. We also examine how mirror neuron activation is related to social cognition (e.g. facial emotion processing, theory of mind, empathy) in these groups.

Future studies of autism and Asperger's disorder include the use of rTMS to improve theory of mind and social functioning, and transcranial direct current stimulation (tDCS) to investigate cerebellar/motor/prefrontal connectivity.